The present invention relates to personal respiratory protection devices that are capable of being folded flat during storage and form an air chamber over the mouth and nose of a wearer during use.
Personal respiratory protection devices, also known as filtration respirators or face masks, are used in a wide variety of applications to protect a wearer""s respiratory system from particles suspended in the air or from unpleasant or noxious gases. Face masks are typically designed to be worn over the nose and the mouth to protect the wearer from undesirable material suspended in the air. Generally, these types of face masks come in two basic designsxe2x80x94a molded cup-shaped form or a flat-folded form.
A conventional flat-folded form of face mask is typically constructed by incorporating a fabric that is rectangular in form and includes at least one pleat running generally parallel to the mouth of the wearer. Such constructions may have a stiffening element to hold the face mask away from contact with the wearer""s face. Stiffening has also been provided by fusing a pleat across the width of the face mask in a laminated structure or by providing a seam across the width of the face mask. In many applications, it is particularly desirable to provide such a face mask having a generally xe2x80x9cflatxe2x80x9d configuration for easy storage prior to donning the face mask. The flat-folded form has advantages in that it can be easily stored, such as in a wearer""s pocket.
It has been found that flat type face masks can conform quite closely to the wearer""s face, that is, most of the inner surface of the mask may come into contact with the face of the wearer. Thus, flat face masks may be warm and uncomfortable during use, and this is particularly true when the face mask is worn for extended periods of time. In addition, the inner surface of the face mask may come into contact with the wearer""s mouth such that the face mask often becomes wet and abraded. When this happens, the abraded material from the inner surface may irritate the wearer.
Cup-shaped masks are typically molded masks that form an air-chamber over the face when in use thereby overcoming some of the comfort concerns related to flat folded masks. However, molded cup-shaped masks may not be folded flat for easy and convenient storage.
U.S. Pat. No. 3,971,369 to Aspelin et al. discloses a generally cup-shaped surgical mask that is not molded. The patent discloses that because the mask is not molded, the edges of the body portion of the mask are not rigid and therefore conform to the contours of the wearer""s face. However, the mask is complicated to manufacture and the resulting design is pleated, having overlapping material on the front of the mask.
International Publication No. WO 96/28217 describes a flat-folded personal respiratory device. In that publication, it is described that the devices include a flat central portion, a flat first member joined to the central portion through either a fold-line, seam, weld, or bond and a flat second member joined to the central portion through either a fold-line, seam, weld, or bond. It is described that the device is capable of being folded flat for storage with the first and second members being in at least partial face to face contact with a common surface of the central portion and, during use, is capable of forming a cup-shaped air chamber over the nose and the mouth of the wearer.
There is a need for a personal respiratory protection device or face mask that is capable of being flat folded, yet provides a good respiratory seal and is comfortable to wear. There is a further need for a mask of uncomplicated design that is relatively easy and inexpensive to manufacture.
One aspect of the present invention provides a personal respiratory protection device including a non-pleated main body. Preferably, the main body includes a first portion; a second portion distinguished from the first portion by a first line of demarcation; a third portion distinguished from the second portion by a second line of demarcation; and a bisecting fold extending through the first portion, second portion and third portion; wherein the device is capable of being folded to a first substantially flat-folded configuration along the bisecting fold and is capable of being unfolded to a convex open configuration.
Preferred embodiments of the device include filter media or include a cover layer. Preferably, the device includes a stiffener layer in at least the second portion. In a preferred embodiment, the device includes a weld-line between the first and second portion which bonds the filter media, cover layer and preferably the stiffener layer together. In a particularly preferred embodiment, the device includes a second weld-line between the second portion and the third portion that bonds the layers together.
A device in accordance with the present invention preferably has the first portion extending from the second portion at an angle of about 110 degrees to about 175 degrees when measured from the bisecting fold extending through the second portion to the bisecting fold extending through the first portion when the device is folded in the substantially flat-folded configuration.
A device in accordance with the present invention preferably has the third portion extending from the second portion at an angle of about 100 degrees to about 165 degrees when measured from the bisecting fold extending through the second portion to the bisecting fold extending through the third portion when the device is folded in the substantially flat-folded configuration.
In another aspect of the present invention, a process for producing respiratory devices of different sizes from preformed blanks of the same size is described. The process includes folding a preformed blank over a bisecting axis to create a preform having a bisecting fold-line and cutting the preform at a first desired angle at a first position relative to the bisecting fold-line, wherein the first desired angle depends on a desired size and fit of the device. The size and fit of the device may be further adjusted by cutting the preform at a second desired angle at a position relative to the bisecting fold-line.
A device in accordance with the present invention may also include an optional constituent such as a face shield, a face seal, a neck cover, and a combination thereof.
Advantageously, a flat-folded face mask in accordance with the present invention preferably contacts the wearer""s face at the periphery of the face mask at an acute angle with minimal facial contact to form a convex- or cup-shaped region over the nose and mouth of the wearer, thereby increasing comfort to the wearer and potentially maximizing the engagement of the perimeter of the face mask to the face of the wearer.
A process in accordance with the present invention is amenable to high speed production methods and may comprise additional steps as needed for attachment of headbands, ear loops, nosepieces, and other typical respiratory device components.